Report of Business Segments (Tables)

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

The following tables summarize the results of the Company's business segments during the threemonths endedJune 30, 2013 and 2012.

Three Months Ended June 30, 2013	Electric Utility		Natural Gas Midstream Operations		Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	574.6	$	166.1	$	—		$	(6.5	)	$	734.2
Cost of goods sold	247.6		129.7		—			(6.7		)	370.6
Gross margin on revenues	327.0		36.4		—			0.2			363.6
Other operation and maintenance	107.0		15.7		(0.7		)	—			122.0
Depreciation and amortization	62.0		9.2		3.2			—			74.4
Taxes other than income	19.9		2.5		0.9			—			23.3
Operating income (loss)	$	138.1	$	9.0	$	(3.4	)	$	0.2		$	143.9
Equity in earnings of unconsolidated affiliates	$	—	$	18.5	$	—		$	—		$	18.5
Investment in unconsolidated affiliates	$	—	$	1,267.2	$	—		$	—		$	1,267.2
Total assets	$	7,453.6	$	1,266.8	$	189.4		$	(61.3	)	$	8,848.5

Three Months Ended June 30, 2012	Electric Utility		Natural Gas Midstream Operations		Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	528.0	$	344.0	$	—		$	(17.0	)	$	855.0
Cost of goods sold	204.6		222.6		—			(17.9		)	409.3
Gross margin on revenues	323.4		121.4		—			0.9			445.7
Other operation and maintenance	114.7		42.7		(4.4		)	—			153.0
Depreciation and amortization	62.7		24.3		3.5			—			90.5
Impairment of assets	—		0.1		—			—			0.1
Taxes other than income	18.2		5.7		0.9			—			24.8
Operating income (loss)	$	127.8	$	48.6	$	—		$	0.9		$	177.3
Total assets	$	6,833.2	$	2,395.3	$	331.4		$	(208.5	)	$	9,351.4

Six Months Ended June 30, 2013	Electric Utility		Natural Gas Midstream Operations		Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	1,030.1	$	630.4	$	—		$	(24.9	)	$	1,635.6
Cost of goods sold	460.6		489.0		—			(26.0		)	923.6
Gross margin on revenues	569.5		141.4		—			1.1			712.0
Other operation and maintenance	212.1		60.9		(3.0		)	—			270.0
Depreciation and amortization	123.3		36.8		6.2			—			166.3
Taxes other than income	43.1		10.5		2.8			—			56.4
Operating income (loss)	$	191.0	$	33.2	$	(6.0	)	$	1.1		$	219.3
Equity in earnings of unconsolidated affiliates	$	—	$	18.5	$	—		$	—		$	18.5
Investment in unconsolidated affiliates	$	—	$	1,267.2	$	—		$	—		$	1,267.2
Total assets	$	7,453.6	$	1,266.8	$	189.4		$	(61.3	)	$	8,848.5

Six Months Ended June 30, 2012	Electric Utility		Natural Gas Midstream Operations			Other Operations			Eliminations			Total
(In millions)
Operating revenues	$	954.7	$	773.6		$	—		$	(32.6	)	$	1,695.7
Cost of goods sold	400.1		527.9			—			(33.4		)	894.6
Gross margin on revenues	554.6		245.7			—			0.8			801.1
Other operation and maintenance	225.3		85.0			(9.7		)	—			300.6
Depreciation and amortization	122.4		47.7			7.0			—			177.1
Impairment of assets	—		0.3			—			—			0.3
Gain on insurance proceeds	—		(7.5		)	—			—			(7.5		)
Taxes other than income	39.3		13.0			2.7			—			55.0
Operating income (loss)	$	167.6	$	107.2		$	—		$	0.8		$	275.6
Total assets	$	6,833.2	$	2,395.3		$	331.4		$	(208.5	)	$	9,351.4